I really appreciated all the pictures and ideas in this thread when I was making a battery box for my bike!

When I bought this box I thought there would be plenty of room for the 36 volt 15 amp hour Ping battery, as it was a couple inches bigger than it needed to be in length and width and about an inch bigger than it needed to be in height. But being completely inexperienced, I did not realize that by the time I added sufficient protective padding, left room for the wires and charging socket, and the inline circuit breaker it was going to be a very tight fit.

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The lid was originally a friction fit, but the box did not have enough depth to accommodate the battery and have the lid fit snugly, so I created a bit more depth by putting the lid on hinges with a locking catch on the other side. I used epoxy to make sure the bolts cannot come undone. And the inside of the box is lined with corrugated plastic, duct tape and closed cell foam. Trying to come up with a home made battery box that is both sturdy, lightweight and theft resistant was a lot more difficult than I anticipated, and as I need to leave my bike locked up in a public place, sometimes for a whole day, I think I still need to create some sort of heavy duty steel lid I can lock down over the whole thing. I am thinking I could probably keep the reinforced lid near where I leave the bike so I do not have to ride with the extra weight. And I may find a better box and redo the whole system. But this will work OK for now!

Kiriakos GR wrote:Why to improvise when engineers have run ahead and design an almost 90% compatible rack for your bicycle ?
All that I had to do is to shorten the rods at half length of the ones who hold still the rack with the frame.

....because putting weight above the rear wheel like that is simply not good - effects on handling are pronounced.

Kiriakos GR wrote:Why to improvise when engineers have run ahead and design an almost 90% compatible rack for your bicycle ?
All that I had to do is to shorten the rods at half length of the ones who hold still the rack with the frame.

....because putting weight above the rear wheel like that is simply not good - effects on handling are pronounced.

That depends on a lot of factors. I find that a suitably rigid rear rack lets me carry up to about 30 lbs back there without objectionable effects, but my pedaling is impaired if I have something wider than about 2" between my knees. Others here obviously differ, or else they don't bother pedaling.

Rear motor/front frame-mounted battery seems like a good layout, but the opposite is what I've usually used. I'd only tolerate a battery in the front triangle if it was situated down low by the cranks.

This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.

With a 4"/100mm wide in the triangle battery box I find it difficult to notice, I can touch it with the knees, but not without making an effort, certainly not an impediment to any type of pedaling.

Weight on the rear rack is very destabilizing and bicycle frames are not stiff in that direction, so they flex and even motorcycles rear racks are not designed for weights over 30 pounds due to the stability prolbems it causes.

Weight high and forward is very stable. Low weight gives that "motor scooter" balance feel, which is slow to control, whereas high forward weight gives the "motorcycle" stability which is very quick and controllable (not so much at very low speed).

Alan B wrote:Weight on the rear rack is very destabilizing and bicycle frames are not stiff in that direction, so they flex and even motorcycles rear racks are not designed for weights over 30 pounds due to the stability prolbems it causes.

While there is a significant inertial moment between mass on a rear rack and a bike's center or rotation in any axis, I have come to believe that most of the problem lies in the rack itself. Most rear luggage racks are made of small diameter aluminum, with no diagonal bracing at all against lateral forces. Both the materials and the designs tend to make them sway side to side under even small loadings.

The Tubus Cargo rack is an example of a rack that differs in both regards. It's made from tubular chromoly steel, and the middle strut forms a triangle joining the rack sides and top. While I don't use this specific rack-- I have found some less expensive ones that do the job I ask of them-- it's the one I order for touring cyclists who load their bikes heavily.

It's not unusual for a self-supported touring cyclist to carry 80 pounds of gear and supplies among two to four panniers. But unlike the lackadaisical pedalers here, self-propelled cyclists don't seem to want anything wider than a water bottle in the front triangle. If you're curious, check out your legs while you pedal. If they move all in a plane parallel to the bike's frame, then all's well. If your knees splay or flare at all as they rise to the top of your pedal stroke, then something is interfering-- a wide battery pack, a too-low seat, or perhaps even a generous belly. I find it doesn't take much to foul my own pedal stroke.

This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.

Just thought I'd udpate this thread... I'm on version 6 of my battery pack design.

First 2 were on the rear rack in 14S2P (This setup is way too dangerous due to risk of wheelie/flipping with a geared hub motor. Front wheel would just lift on takeoffs if I wasnt careful with the throttle). Version 1 was a plastic box which ripped itself apart on the first day of riding over bumps. Version 2 was a metal box (again on rear rack) which ripped itself apart when I was doored (like a flying missile hitting you from behind as the bolts holding it down sheared).
3rd version was in frame but 14cm wide in 14S3P. I'd hit knees and thighs... and just felt uncomfortable to ride as my legs needed to be spread out.
4th version was smaller in frame in 14S2P (12cm wide)
5th version was small frame bag in 14S1P (7cm wide) but didnt have enough juice to carry me for the full commute during strong winds. I needed to go back to 14S2P. I was also conscious that there was no padding on the sides and the straps holding the bag to the top tube kept on fraying/ripping due to battery weight. Missus had to repair it twice before I took on version 6.

6th Version : 14S2P setup 6.7cm wide.

I'm short, so bike is a size small (16") but wheels are 29er. I really dont have much room in the frame =(

Chalo wrote:
That depends on a lot of factors. I find that a suitably rigid rear rack lets me carry up to about 30 lbs back there without objectionable effects, but my pedaling is impaired if I have something wider than about 2" between my knees. Others here obviously differ, or else they don't bother pedaling.

Rear motor/front frame-mounted battery seems like a good layout, but the opposite is what I've usually used. I'd only tolerate a battery in the front triangle if it was situated down low by the cranks.

Have you tried a triangle battery, or is this a theory?

Water bottles are wider than 2". I can easily put 500 watts pedal power into the system (for a short time) and I can't tell at all that there is a 100mm wide battery compartment there or not. I've never contacted it except when I stop pedaling and specifically tuck in to it. The pedals are considerably wider than 120mm apart on the inside pedal edge. At least for me, 100mm battery width is insufficient to be noticed, and I've never consciously adjusted my pedaling to allow for the width.

Chalo wrote:

Alan B wrote:Weight on the rear rack is very destabilizing and bicycle frames are not stiff in that direction, so they flex and even motorcycles rear racks are not designed for weights over 30 pounds due to the stability problems it causes.

While there is a significant inertial moment between mass on a rear rack and a bike's center or rotation in any axis, I have come to believe that most of the problem lies in the rack itself. Most rear luggage racks are made of small diameter aluminum, with no diagonal bracing at all against lateral forces. Both the materials and the designs tend to make them sway side to side under even small loadings.

The Tubus Cargo rack is an example of a rack that differs in both regards. It's made from tubular chromoly steel, and the middle strut forms a triangle joining the rack sides and top. While I don't use this specific rack-- I have found some less expensive ones that do the job I ask of them-- it's the one I order for touring cyclists who load their bikes heavily.

It's not unusual for a self-supported touring cyclist to carry 80 pounds of gear and supplies among two to four panniers. But unlike the lackadaisical pedalers here, self-propelled cyclists don't seem to want anything wider than a water bottle in the front triangle. If you're curious, check out your legs while you pedal. If they move all in a plane parallel to the bike's frame, then all's well. If your knees splay or flare at all as they rise to the top of your pedal stroke, then something is interfering-- a wide battery pack, a too-low seat, or perhaps even a generous belly. I find it doesn't take much to foul my own pedal stroke.

The weight distribution issue is not about pedaling, it is about stability. Poking along at low speed it may not matter much, but try and execute a quick S-turn and the rear weight will have significant input into the steering and reduce the stability and safety of the vehicle.

As you well know, touring cyclists carry most of the weight low, not above the rack, and only a part of it is on the rear. So in total an 80 pound load is effectively less than 30 pounds on the rear rack. If half was on the front, and the remainder is centered about the rear axle, the effective weight on the rear rack is about 20 pounds. Also a heavy loaded touring bike is hardly a good handling machine, and is not very safe at high speed.

In an attempt to bring this thread back on topic,

The EM3EV triangle bag is about 80mm wide, so even less than 4", and pretty much equal to a water bottle. My Mountain bike battery in the triangle is 100mm wide (side by side Turnigy 6S5AH packs), and the bikeE battery is about 65mm wide with PVC gutter material and single Zippy 6S 8AH packs. So, in my experience a width of 80 to 100mm is narrow enough for a battery compartment. The standard Greyborg compartment is 100mm inside, so a few more mm outside the plastic.

As mentioned above, My first 2 versions were rear rack mounted and the weight on the rear rack made the bike want to keep on lifting the front wheel and possibly killing me. It was even worse trying to go up a hill or mountain trail. If you're doing less than 2kw I guess it's ok as there isnt the instant snatching torque and the top speed of > 30mph. But yeah... I'm 100% convert to middle frame mount.

Chalo wrote:I'd only tolerate a battery in the front triangle if it was situated down low by the cranks.

Have you tried a triangle battery, or is this a theory?

Water bottles are wider than 2".

I have never bothered to try a triangle battery, because my experience with smaller items (e.g. water bottles) in triangle bags has demonstrated that my knees rub on them when I pedal. Water bottles are a little wider than 2", but they don't occupy the space swept by the rider's knees. So bottle batteries make sense to me, but triangle batteries do not.

Bowlegged riders, or those who never had a proven pedaling form to deviate from, may have no problem stuffing their front triangles with whatever they choose.

This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.

Chalo wrote:I'd only tolerate a battery in the front triangle if it was situated down low by the cranks.

Have you tried a triangle battery, or is this a theory?

Water bottles are wider than 2".

I have never bothered to try a triangle battery, because my experience with smaller items (e.g. water bottles) in triangle bags has demonstrated that my knees rub on them when I pedal. Water bottles are a little wider than 2", but they don't occupy the space swept by the rider's knees. So bottle batteries make sense to me, but triangle batteries do not.

Bowlegged riders, or those who never had a proven pedaling form to deviate from, may have no problem stuffing their front triangles with whatever they choose.

It sounds like you have an unusual problem there. No one else seems to have that complaint, but everyone is built a bit different.

Just got done reading this hole thread. There is some great stuff here!
Gave me a lot of great Ideas for when I revamp my commuter and for my current build. Thanks to all.
Just one question? How come nobody seems to do front fork pannier style battery mounting?
I put 48V 40Ah lipo in two front panniers 20Ah in each. I road that all last summer and I had no problems with handling.
Granted the bike only went 23.5 MPH on the flats, but I didn't feel it in the steering or balance.
I could even let go of the handle bars unscrew my tasty beverage, take a drink, screw the cap back on and put said drink back in the cup holder no prob.
Also it evens out the weight, with the hubbie in the rear.
The only negative was the bumpiness of the ride with all that weight in the front. (I wonder if a front suspension fork will fix this?)
I originally was going to put another 40Ah in the rear pannier too but it turned out that 50 miles to charge was just enough for what I needed. No peddling, unless I was in a hurry or there was a big hill.
I just used the rear for lunch box, groceries, ect...
Here's a link to some pics. I'll put some here as well.https://endless-sphere.com/forums/viewto ... 25#p990800
This is by no means custom, just thought it might be appropriate.

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pic shows parallel balance charging all batteries, I could actually just barely fit the charger in the triangle bag, controller is in the seat post bag.

diggler wrote:Just got done reading this hole thread. There is some great stuff here!
Gave me a lot of great Ideas for when I revamp my commuter and for my current build. Thanks to all.
Just one question? How come nobody seems to do front fork pannier style battery mounting?
I put 48V 40Ah lipo in two front panniers 20Ah in each. I road that all last summer and I had no problems with handling.
Granted the bike only went 23.5 MPH on the flats, but I didn't feel it in the steering or balance.
I could even let go of the handle bars unscrew my tasty beverage, take a drink, screw the cap back on and put said drink back in the cup holder no prob.
Also it evens out the weight, with the hubbie in the rear.
The only negative was the bumpiness of the ride with all that weight in the front. (I wonder if a front suspension fork will fix this?)
I originally was going to put another 40Ah in the rear pannier too but it turned out that 50 miles to charge was just enough for what I needed. No peddling, unless I was in a hurry or there was a big hill.
I just used the rear for lunch box, groceries, ect...
Here's a link to some pics. I'll put some here as well.https://endless-sphere.com/forums/viewto ... 25#p990800
This is by no means custom, just thought it might be appropriate.

Jesus Christ!.... And I thought my wiring harness was a handful. What kind of pack configuration are you running there?

Batt box made out of 3 5/8 steel bottom track used uncommercial buildings and bought at Home Depot for $5.50. Sides are galv. Sheet metal cut to doze of the frame. Waterproof switch connected at controller and a panel mount XLR port for charging

Okay thanks amberwolf. I got some good idea's from this thread too. I plan on putting one 6s 16ah batt. on each side of the fork on my SIKK gas/electric, in a hard case. Then one in a harley type handle bar bag for 18s 16ah total up front. Then 24 headways in ammo boxes in the rear hard mounted and covered with saddle bags.

Haha danielrlee, each bank was 3s 1,000,001p! haha no seriously I just bought the most amount of ah in a 3s for the $1 and I already had most of the 15 3s 5ah from earlier when I was running 15s 15ah. I say most cause I fried some by running them too low. So in the picture 1 bank was 3- 5ah's, 1- 3ah and 10- 2.2ah's! Equaling 40ah. So that's 3s 14p on each bank and 4 banks so that's 56 grade B lipo's for the entire pack! All soldered to 10awg taking one entire day! Parallel balance charged them every time with a 300w 20A thunder and at first it only took ~2.5hrs then when the pack became out of balance I noticed it starting to take longer and longer until finally it would sit there and balance them all night. I got the hole pack apart now and I'm self discharge testing them right now. Then I'll capacity test them and rebuild them into a balanced pack again.

Mine is a TIG - welded chequer plate alu box, secured to the box section bike frame using chunky video camera mounts that simply snap on and off by pressing a small lever. Great for easy removal for charging indoors etc.
Very solid too - secured by two M8 stainless bolts right through the Frame. It's butch rather than pretty!!

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“Begin doing what you want to do now. We are not living in eternity. We have only this moment, sparkling like a star in our hand and melting like a snowflake...” Francis Bacon

My reasoning was to keep the centre of gravity low and central, like a motorcycle engine. I progressed through plenty of ideas before I settled on this solution, thanks to the weird angles of my frame and the necessary size of the batt pack. (19s 6p - 18650 Samsungs)

“Begin doing what you want to do now. We are not living in eternity. We have only this moment, sparkling like a star in our hand and melting like a snowflake...” Francis Bacon

Hi Diggler, the little nose fairing was an EBay special - about £15 if I remember correctly. I took a hacksaw to the light enclosures and grafted in a couple of Cree 1200LM torches, one for solid light, the other flashes rapidly to attract attention. Overkill, yes. Roadkill, hopefully No!!

“Begin doing what you want to do now. We are not living in eternity. We have only this moment, sparkling like a star in our hand and melting like a snowflake...” Francis Bacon

Alan B wrote:Weight on the rear rack is very destabilizing and bicycle frames are not stiff in that direction, so they flex and even motorcycles rear racks are not designed for weights over 30 pounds due to the stability prolbems it causes.

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My little KE100 moto is pretty solid. I had 150lbs of SLAs up and behind my seat (going to metal scrapper). I did have issues with bottoming out the suspension everywhere, and low speed directional changes, but the frame itself was solid. Once up to speed there was no oscillating or lack of control. My ebike with custom made rear rack from crutches and screws (not welded) is just the opposite. It has trouble with oscillating.

I like the repurposing of off the shelf brackets and parts like the camera brackets mentioning earlier. Not everyone has a milling machine or CNC handy so to be able to use off the shelf parts makes a lot of sense.

I reused a battery box from an earlier project and mounted it using 32mm clamps designed to mount spot lights onto the bulbar of a 4WD or truck. It saves welding to a stock frame if you want to remove the battery pack later and return the bike to its original condition. These clamps have rubber between the clamp and the tube. When done up there is no way it will move.